However, Nadal, who has not played since Wimbledon, has now pulled out of next week's Qatar Open and will not feature at the first major of the year, which begins in Melbourne on January 14.

"I am sorry and very sad to announce that I will not play in the Australian Open," Nadal said. "My knee is coming along okay, but a stomach virus has left me unable to get ready in time to tackle the rigours of a grand slam.

"Because of the virus, I have been unable to get any match practice and simply would not be doing myself or my friends in Australia justice if I went down there so unprepared. You need your body to be at its best for the Australian Open."

Tournament director Craig Tiley said: "It is completely understandable and we really feel disappointed for him. But without any match practice and without sufficient lead up time on the practice court, it makes it virtually impossible for him to get his body ready.

"We just hope he gets better quickly and we see him back on the tour as soon as possible. Tennis fans across the world have been missing him."

In missing the Australian Open, Nadal will drop out of the top four in the world rankings for the first time since May 2005, when he won his first of seven French Open titles.

"It is true we have been quite unlucky with this but there is nothing we can do," Toni Nadal, Rafa's uncle, added. "[But] It is simply inconceivable that his first event is a best of five sets event, he wouldn't be ready for that."

The 2009 Australian Open champion is expected to make a return to competitive action on the clay in Acapulco in February.